Zenmetsu End wo Shi ni Monogurui de Kaihi shita. Party ga Yanda.

"...Wolka?! Noooooo!! Y-you can't die on me!!" Wolka, an adventurer, is a reincarnator from Japan. During a dungeon exploration, his party is ambushed by a powerful monster, and Wolka suffers fatal injuries while protecting his companions; in his final moments, he finally remembers the world he had reincarnated into was that of a dark fantasy manga he read in his previous life — that he and his companions were minor characters to be annihilated then and there. But Wolka, empowered by his hatred for bad endings, desperately presses on for the sake of his companions — and defeats the monster. It only cost him an eye and a leg — but in exchange, he and his party escaped their intended fate. What he did not account for, however, was how the experience changed the young girls that were his companions. "I swear I'll protect you this time!! So please, please, don't abandon me..!" "I'll always be by your side... You're fine with that, right, senpai?" "I would give my life for yours... That is what I decided." This is the murky, otherworldly story of a reincarnated man who values happy endings above all and the girls who harbor intense feelings for him! (Source: Kadokawa, translated)